// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SOCKET_TCP_SOCKET_POSIX_H_
#define NET_SOCKET_TCP_SOCKET_POSIX_H_

#include <stdint.h>

#include <memory>

#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/time/time.h"
#include "net/base/address_family.h"
#include "net/base/completion_callback.h"
#include "net/base/net_export.h"
#include "net/log/net_log.h"
#include "net/socket/socket_performance_watcher.h"

namespace base {
class TickClock;
}

namespace net {

class AddressList;
class IOBuffer;
class IPEndPoint;
class SocketPosix;

class NET_EXPORT TCPSocketPosix {
public:
    // |socket_performance_watcher| is notified of the performance metrics related
    // to this socket. |socket_performance_watcher| may be null.
    TCPSocketPosix(
        std::unique_ptr<SocketPerformanceWatcher> socket_performance_watcher,
        NetLog* net_log,
        const NetLog::Source& source);
    virtual ~TCPSocketPosix();

    int Open(AddressFamily family);
    // Takes ownership of |socket_fd|.
    int AdoptConnectedSocket(int socket_fd, const IPEndPoint& peer_address);

    int Bind(const IPEndPoint& address);

    int Listen(int backlog);
    int Accept(std::unique_ptr<TCPSocketPosix>* socket,
        IPEndPoint* address,
        const CompletionCallback& callback);

    int Connect(const IPEndPoint& address, const CompletionCallback& callback);
    bool IsConnected() const;
    bool IsConnectedAndIdle() const;

    // Multiple outstanding requests are not supported.
    // Full duplex mode (reading and writing at the same time) is supported.
    int Read(IOBuffer* buf, int buf_len, const CompletionCallback& callback);
    int Write(IOBuffer* buf, int buf_len, const CompletionCallback& callback);

    int GetLocalAddress(IPEndPoint* address) const;
    int GetPeerAddress(IPEndPoint* address) const;

    // Sets various socket options.
    // The commonly used options for server listening sockets:
    // - SetAddressReuse(true).
    int SetDefaultOptionsForServer();
    // The commonly used options for client sockets and accepted sockets:
    // - SetNoDelay(true);
    // - SetKeepAlive(true, 45).
    void SetDefaultOptionsForClient();
    int SetAddressReuse(bool allow);
    int SetReceiveBufferSize(int32_t size);
    int SetSendBufferSize(int32_t size);
    bool SetKeepAlive(bool enable, int delay);
    bool SetNoDelay(bool no_delay);

    // Gets the estimated RTT. Returns false if the RTT is
    // unavailable. May also return false when estimated RTT is 0.
    bool GetEstimatedRoundTripTime(base::TimeDelta* out_rtt) const
        WARN_UNUSED_RESULT;

    void Close();

    void EnableTCPFastOpenIfSupported();

    bool IsValid() const;

    // Detachs from the current thread, to allow the socket to be transferred to
    // a new thread. Should only be called when the object is no longer used by
    // the old thread.
    void DetachFromThread();

    // Marks the start/end of a series of connect attempts for logging purpose.
    //
    // TCPClientSocket may attempt to connect to multiple addresses until it
    // succeeds in establishing a connection. The corresponding log will have
    // multiple NetLog::TYPE_TCP_CONNECT_ATTEMPT entries nested within a
    // NetLog::TYPE_TCP_CONNECT. These methods set the start/end of
    // NetLog::TYPE_TCP_CONNECT.
    //
    // TODO(yzshen): Change logging format and let TCPClientSocket log the
    // start/end of a series of connect attempts itself.
    void StartLoggingMultipleConnectAttempts(const AddressList& addresses);
    void EndLoggingMultipleConnectAttempts(int net_error);

    void SetTickClockForTesting(std::unique_ptr<base::TickClock> tick_clock);

    const BoundNetLog& net_log() const { return net_log_; }

private:
    // States that using a socket with TCP FastOpen can lead to.
    enum TCPFastOpenStatus {
        TCP_FASTOPEN_STATUS_UNKNOWN,

        // The initial FastOpen connect attempted returned synchronously,
        // indicating that we had and sent a cookie along with the initial data.
        TCP_FASTOPEN_FAST_CONNECT_RETURN,

        // The initial FastOpen connect attempted returned asynchronously,
        // indicating that we did not have a cookie for the server.
        TCP_FASTOPEN_SLOW_CONNECT_RETURN,

        // Some other error occurred on connection, so we couldn't tell if
        // FastOpen would have worked.
        TCP_FASTOPEN_ERROR,

        // An attempt to do a FastOpen succeeded immediately
        // (TCP_FASTOPEN_FAST_CONNECT_RETURN) and we later confirmed that the server
        // had acked the data we sent.
        TCP_FASTOPEN_SYN_DATA_ACK,

        // An attempt to do a FastOpen succeeded immediately
        // (TCP_FASTOPEN_FAST_CONNECT_RETURN) and we later confirmed that the server
        // had nacked the data we sent.
        TCP_FASTOPEN_SYN_DATA_NACK,

        // An attempt to do a FastOpen succeeded immediately
        // (TCP_FASTOPEN_FAST_CONNECT_RETURN) and our probe to determine if the
        // socket was using FastOpen failed.
        TCP_FASTOPEN_SYN_DATA_GETSOCKOPT_FAILED,

        // An attempt to do a FastOpen failed (TCP_FASTOPEN_SLOW_CONNECT_RETURN)
        // and we later confirmed that the server had acked initial data.  This
        // should never happen (we didn't send data, so it shouldn't have
        // been acked).
        TCP_FASTOPEN_NO_SYN_DATA_ACK,

        // An attempt to do a FastOpen failed (TCP_FASTOPEN_SLOW_CONNECT_RETURN)
        // and we later discovered that the server had nacked initial data.  This
        // is the expected case results for TCP_FASTOPEN_SLOW_CONNECT_RETURN.
        TCP_FASTOPEN_NO_SYN_DATA_NACK,

        // An attempt to do a FastOpen failed (TCP_FASTOPEN_SLOW_CONNECT_RETURN)
        // and our later probe for ack/nack state failed.
        TCP_FASTOPEN_NO_SYN_DATA_GETSOCKOPT_FAILED,

        // The initial FastOpen connect+write succeeded immediately
        // (TCP_FASTOPEN_FAST_CONNECT_RETURN) and a subsequent attempt to read from
        // the connection failed.
        TCP_FASTOPEN_FAST_CONNECT_READ_FAILED,

        // The initial FastOpen connect+write failed
        // (TCP_FASTOPEN_SLOW_CONNECT_RETURN)
        // and a subsequent attempt to read from the connection failed.
        TCP_FASTOPEN_SLOW_CONNECT_READ_FAILED,

        // We didn't try FastOpen because it had failed in the past
        // (g_tcp_fastopen_has_failed was true.)
        // NOTE: This status is currently registered before a connect/write call
        // is attempted, and may capture some cases where the status is registered
        // but no connect is subsequently attempted.
        // TODO(jri): The expectation is that such cases are not the common case
        // with TCP FastOpen for SSL sockets however. Change code to be more
        // accurate when TCP FastOpen is used for more than just SSL sockets.
        TCP_FASTOPEN_PREVIOUSLY_FAILED,

        TCP_FASTOPEN_MAX_VALUE
    };

    void AcceptCompleted(std::unique_ptr<TCPSocketPosix>* tcp_socket,
        IPEndPoint* address,
        const CompletionCallback& callback,
        int rv);
    int HandleAcceptCompleted(std::unique_ptr<TCPSocketPosix>* tcp_socket,
        IPEndPoint* address,
        int rv);
    int BuildTcpSocketPosix(std::unique_ptr<TCPSocketPosix>* tcp_socket,
        IPEndPoint* address);

    void ConnectCompleted(const CompletionCallback& callback, int rv);
    int HandleConnectCompleted(int rv);
    void LogConnectBegin(const AddressList& addresses) const;
    void LogConnectEnd(int net_error) const;

    void ReadCompleted(const scoped_refptr<IOBuffer>& buf,
        const CompletionCallback& callback,
        int rv);
    int HandleReadCompleted(IOBuffer* buf, int rv);

    void WriteCompleted(const scoped_refptr<IOBuffer>& buf,
        const CompletionCallback& callback,
        int rv);
    int HandleWriteCompleted(IOBuffer* buf, int rv);
    int TcpFastOpenWrite(IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback);

    // Notifies |socket_performance_watcher_| of the latest RTT estimate available
    // from the tcp_info struct for this TCP socket.
    void NotifySocketPerformanceWatcher();

    // Called after the first read completes on a TCP FastOpen socket.
    void UpdateTCPFastOpenStatusAfterRead();

    std::unique_ptr<SocketPosix> socket_;
    std::unique_ptr<SocketPosix> accept_socket_;

    // Socket performance statistics (such as RTT) are reported to the
    // |socket_performance_watcher_|. May be nullptr.
    std::unique_ptr<SocketPerformanceWatcher> socket_performance_watcher_;

    std::unique_ptr<base::TickClock> tick_clock_;

    // Minimum interval betweeen consecutive notifications to
    // |socket_performance_watcher_|.
    const base::TimeDelta rtt_notifications_minimum_interval_;

    // Time when the |socket_performance_watcher_| was last notified of updated
    // RTT.
    base::TimeTicks last_rtt_notification_;

    // Enables experimental TCP FastOpen option.
    bool use_tcp_fastopen_;

    // True when TCP FastOpen is in use and we have attempted the
    // connect with write.
    bool tcp_fastopen_write_attempted_;

    // True when TCP FastOpen is in use and we have done the connect.
    bool tcp_fastopen_connected_;

    TCPFastOpenStatus tcp_fastopen_status_;

    bool logging_multiple_connect_attempts_;

    BoundNetLog net_log_;

    DISALLOW_COPY_AND_ASSIGN(TCPSocketPosix);
};

} // namespace net

#endif // NET_SOCKET_TCP_SOCKET_POSIX_H_
